1. Field of Invention
The present invention relates to a magnetic device such as an inductor, a filter or a transformer.
2. Related Art
Taking the conventional inductor as an example, it is usually made by directly winding an enameled wire on a material with the magnetic induction property. When the current is applied to the inductor, the inductance can be obtained. As shown in FIG. 1, a conventional inductor 1 includes an insulating housing 11, an iron core 12 and two enameled wires 13. The iron core 12 is an annular iron core, and the insulating housing 11 covers the iron core 12. The enameled wires 13 are wound on the iron core 12 by hand or machine.
In the conventional winding method, the enameled wires 13 are usually wound repeatedly and repeatedly so as to obtain larger inductance. However, this may scratch the insulating layer of the enameled wires 13. In addition, the winding distribution of the wires may be non-uniform due to the different winding methods and directions. Therefore, the stray capacitance of the inductor becomes uncontrollable, which results in the increasing variation of noise restraining ability between the coils with the same specification. In addition, after winding the enameled wires 13, the ends of the enameled wires 13 are usually pulled to make the enameled wires 13 more tightly fit on the iron core 12. Accordingly, the redundant portions of the enameled wires 13 must be waived. Moreover, the conventional winding method needs much manufacturing time, so that the manufacturing cost is increased.